TUESDAY, Sept. 12 (HealthDay News) -- The antidepressant drug Prozac (fluoxetine) can disrupt the reproductive cycle of freshwater mussels and increase their risk of extinction, says a U.S. study presented Monday at the national meeting of the American Chemical Society, in San Francisco.

As with other drugs, remnants of Prozac are flushed from the body and travel in wastewater that reaches streams and rivers.

This study found that the drug causes female mussels to release their larvae before they're able to survive on their own.

"The results from this study were quite alarming. When larvae are released too early, they are not viable, which only contributes to the problems faced by struggling populations of native freshwater mussels," co-investigator Rebecca Heltsley of the U.S. National Institute of Standards and Technology, Hollings Marine Laboratory in Charleston, N.C., said in a prepared statement.

About 70 percent of the nearly 300 species of native North American freshwater mussels are extinct, endangered or in decline due to pollution, loss or alteration of habitat, increased sediment in rivers, and competition from invasive foreign species.

"The presence of Prozac and similar drugs in U.S. rivers and streams has likely compounded the problem. It's a big concern because freshwater mussels are such an imperiled group," Heltsley said.

"Protecting freshwater mussels and other aquatic life that are susceptible to the unintended consequences of exposure to pharmaceuticals in our rivers and streams will take a concentrated effort," she said. "These efforts could include the development of more efficient wastewater treatment facilities that can filter out these products before they reach our waterways."